HALOGENS

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Molecules of fluorine, chlorine, bromine and iodine and diatomic molecules. Astatine is synthesized artificially and it only exist in traces.

Intermolecular interactions are very weak in diatomic molecules of halogens, so fluorine molecule is a gas whose color is closer to green. It is very difficult to obtain the liquid. Talking about chlorine molecule, we can say that it is a yellow gas. We can obtain it liquid in high pressure. Bromine molecules is a red liquid, and iodine molecule is a black solid; It seems a metal and iodine sublimes, so we can get the vapor directly from the solid state.

 We can explain the color thinking that going down the group of halogens, the number of orbitals is higher and the difference between the levels of energy is less, so transits of electrons from one level to another is easier.